4-Amino­pyridinium 5-carb­oxy­penta­noate monohydrate

S Alfred Cecil Raj; A Sinthiya; Babu Varghese

doi:10.1107/S1600536812027638

. 2012 Jun 23;68(Pt 7):o2181. doi: 10.1107/S1600536812027638

4-Aminopyridinium 5-carboxypentanoate monohydrate

S Alfred Cecil Raj ^a,^*, A Sinthiya ^a, Babu Varghese ^b

PMCID: PMC3393984 PMID: 22798849

Abstract

In the title hydrated salt, C₅H₇N₂ ⁺·C₆H₉O₄ ⁻·H₂O, the carboxy H atom is disordered over two positions with equal occupancy. In the crystal, O atoms of the 5-carboxypentanoate anion link the 4-aminopyridinium cations and water molecules into a three-dimensional network via N—H⋯O hydrogen bonds. The crystal structure is further consolidated by O—H⋯O hydrogen bonds involving the anion and the solvent water molecule.

Related literature

For the biological activity of 4-aminopyridine, see: Judge & Bever (2006 ▶); Schwid et al. (1997 ▶); Strupp et al. (2004 ▶). For related structures, see: Anderson et al. (2005 ▶); Chao & Schempp (1977 ▶); Goswami & Ghosh (1997 ▶).

Experimental

Crystal data

C₅H₇N₂ ⁺·C₆H₉O₄ ⁻·H₂O
M _r = 258.27
Monoclinic,
a = 11.9874 (6) Å
b = 5.1197 (2) Å
c = 21.5045 (9) Å
β = 96.498 (2)°
V = 1311.29 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 296 K
0.30 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.970, T _max = 0.980
21231 measured reflections
3232 independent reflections
2737 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.038
wR(F ²) = 0.110
S = 1.04
3232 reflections
184 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812027638/bt5875sup1.cif

e-68-o2181-sup1.cif^{(21.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812027638/bt5875Isup2.hkl

e-68-o2181-Isup2.hkl^{(158.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812027638/bt5875Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2C⋯O2ⁱ	0.82	1.63	2.4493 (18)	173
N1—H1A⋯O1ⁱ	0.88 (1)	1.93 (1)	2.7694 (15)	159 (2)
O4—H4C⋯O4ⁱⁱ	0.82	1.62	2.4320 (15)	168
N2—H2A⋯O3ⁱⁱ	0.88 (1)	1.96 (1)	2.8433 (13)	173 (1)
O1S—H1S⋯O1ⁱⁱⁱ	0.85 (2)	1.98 (2)	2.8060 (16)	163 (2)
O1S—H2S⋯O1S ^iv	0.85 (2)	1.97 (2)	2.8180 (11)	174 (2)
N2—H2B⋯O3^v	0.88 (1)	2.07 (1)	2.9122 (13)	161 (1)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

The authors thank the Director, Sophisticated Test and Instrumention Center, Cochin University, Kerala, India, for the data collection and the Head of the Department of Physics, St Josephs College, Tamil Nadu, India, for his encouragement.

supplementary crystallographic information

Comment

4-Aminopyridine (Fampridine) is clinically used in the treatment of Lambert-Eaton myasthenic syndrome and multiple sclerosis. It prolongs action potentials by blocking potassium channels, thereby increases transmitter release at the neuromuscular junction (Judge & Bever, 2006; Schwid et al., 1997; Strupp et al., 2004). Hydrogen bonding plays a key role in the molecular recognition (Goswami & Ghosh, 1997).

The asymmetric unit of the title compound C₅H₇N₂,C₆H₉O₄,H₂O contains one 4-aminopyridinium cation, one hydrogen adipate anion and one water molecule. In the hydrogen adipate anion the hydrogen atom of the COOH group is equally disordered (50:50) over two atomic sites. Figure 1 shows the asymmetric unit of the title compound C₅H₇N₂,C₆H₉O₄,H₂O, showing 30% displacement ellipsoid probability and the atom numbering scheme. Cation link the oxygen ends of two adjacent carboxylate of anions. Bonding of the H atom to both pyridine ring N atom and amine group N atom of 4-aminopyridinium gives an ion to give the resonance structure.

The bond lengths and angles of 4-aminopyridinium cation agree with those previously reported (Chao & Schempp, 1977; Anderson et al., 2005). A decrease in the C1–N2 bond length 1.3243 (17) Å is observed. Protonation of N1 of the 4-aminopyridinium results in widening of the C4–N1–C3, 120.41 (13)° which is 115.25 (3)° in the neutral 4-aminopyridinium molecule (Chao & Schempp, 1977; Anderson et al., 2005).

In the molecular packing the title compound is mainly decided by N—H···O and O—H···O hydrogen bonds. The 4-aminopyridinium cations and hydrogen adipate anions are linked through two N—H···O and O—H···O hydrogen bonds (Table 1) forming an infinite molecular chain built from R₄⁴(23) motif. The adjacent lattice water molecules in the crystal is linked through O1S—H2S···O1 hydrogen bond forming an infinite water chain extending along the [0 1 0] direction and the water chains connects the adjacent anionic-cationic chain building up a three dimensional network thus stabilizing the crystalline solid. The hydrogen bonded network is shown in Figure 2

Experimental

All the reagents used for the preparation of sample are analytical grade and the solutions are prepared using pure deionized water. Solutions of 4 aminopyridine and adipic acid in water (20 ml) each are mixed in molar ratio of one isto two. The solution was uniformly stirred for 30 min and heated at 303 K for 2 h. The resulting solution was allowed to cool slowly to room temperature. Colorless crystals were obtained by slow evaporation after a period of two weeks.